The present disclosure relates to processes for manufacturing salt systems containing beryllium fluoride.
Current designs of nuclear fusion and fusion/fission reactors have considered the use of liquid lithium beryllium fluoride (FLiBe) as a cooling medium for various parts of the reactor. FLiBe can also be used to breed tritium, which can be harvested in fusion reactions to make new fusion targets.
FLiBe is a salt of lithium fluoride and beryllium fluoride of varying ratios. This lithium beryllium fluoride has been used extensively in its liquid state as a heat exchange fluid in applications such as solar energy storage, molten salt fission reactors, and fusion reactors, as well as in the electrochemical production of beryllium metal. The low melting point of beryllium fluoride and the fact that its combination with lithium fluoride produces a eutectic with a low melting point is very suitable for such applications. For molten salt reactors, the optimum molten salt is one with a low vapor pressure, low melting point, and high heat capacity, and FLiBe provides all of these characteristics. FLiBe is also being considered for use in fission reactors that use thorium as a fuel.
The traditional method of producing lithium beryllium fluoride has been through the direct co-melting of lithium fluoride and beryllium fluoride in a controlled atmosphere, as shown in Reaction (1):2LiF+BeF2→Li2BeF4  (1)
This reaction is slightly exothermic (ΔH at 1000° C.=−2.59 kcal/mol), but the free energy (ΔG at 1000° C.=−11.7 kcal/mol) is also slightly negative. The log K value for this reaction is 2.01, which is very low and indicates that the reaction does not proceed completely to form FLiBe.
It would be desirable to provide processes for obtaining lithium beryllium fluoride salts that can be simpler and/or result in greater conversion of reactants to product.